Kuroda S, Fowler B O
Calcif Tissue Int. 1984 Jul;36(4):361-9. doi: 10.1007/BF02405347.
Tooth enamel laser irradiated under certain conditions previously has been shown to have reduced subsurface demineralization rates. Identification of these laser-induced changes has bearing on understanding the dissolution rate reduction mechanism; some of these changes, ones that occur in high temperature regions, were studied in this report. X-ray diffraction and infrared spectroscopy were used to identify changes in enamel of extracted intact human teeth subjected to high energy density (approximately 10,000 J/cm2) 10.6 microns wavelength carbon dioxide laser irradiance. The laser irradiance melted the enamel apatite; this solidified melt was composed of minor phases of alpha-tricalcium phosphate, alpha-Ca3 (PO4)2, and tetracalcium phosphate, Ca4(PO4)2O, and a major phase of modified apatite. The apatite modifications, as compared with the original were (1) reductions in contents of water, protein, carbonate, and chloride (or chloride rearrangement); (2) essentially no change in apatite hydroxide content; (3) possible incorporation of oxide replacing some hydroxide ions; and (4) an uptake of traces of carbon dioxide and cyanate. An infrared band at 434 cm-1 that appears in spectra of hydroxyapatite partially dehydroxylated by thermal treatment was assigned to oxide translation. This band was utilized to search for oxide formation in the laser-irradiated tooth enamel.
先前已表明，在特定条件下用激光照射牙釉质，其表面下脱矿率会降低。识别这些激光诱导的变化有助于理解溶解速率降低的机制；本报告研究了其中一些发生在高温区域的变化。利用X射线衍射和红外光谱法来识别完整拔除的人牙釉质在受到高能量密度（约10,000 J/cm²）、波长10.6微米的二氧化碳激光辐照后的变化。激光辐照使牙釉质磷灰石熔化；这种凝固的熔体由少量的α-磷酸三钙、α-Ca3(PO4)2和磷酸四钙Ca4(PO4)2O以及改性磷灰石的主要相组成。与原始磷灰石相比，磷灰石的改性包括：（1）水、蛋白质、碳酸盐和氯的含量降低（或氯的重排）；（2）磷灰石氢氧化物含量基本无变化；（3）可能有氧化物掺入取代了一些氢氧根离子；（4）吸收了微量的二氧化碳和氰酸盐。在经热处理部分脱羟基的羟基磷灰石光谱中出现的434 cm-1处的红外波段被归因于氧化物平移。利用该波段来寻找激光辐照牙釉质中氧化物的形成。
